see also:

• ED Mx of stroke
• vertigo - peripheral vs central
• ED Mx of vertigo and BPV

• HINTS is a 3-part neurologic exam designed to improve the sensitivity for detection of stroke in patients with acute vertigo / acute vestibular syndrome (AVS) compared with CT scanning and consists of:
  • Head Impulse test
  • Nystagmus - fast phase alternating with gaze direction suggests central cause
  • Test of Skew
• CT scan has a low sensitivity for detecting posterior circulation stroke, while acute MRI scanning is better at 88% sensitivity but is not readily available in many centres

• Head impulse test
  • Head is rapidly rotated 20-40 degrees to one side or the other
  • Observe for one eye that lags in response to maintain forward gaze
    • Makes quick saccade movement to catch-up or correct
  • “Normal” test (no saccade/correction on head provocation) strongly suggests posterior CVA
    • specificity for stroke approaches 100%, but sensitivity is only 85%
    • thus while saccade/correction on testing suggests peripheral cause, it does not exclude posterior CVA
  • this is technically difficult as ideally one needs a slow motion video to reliably visualise the response
• Nystagmus
  • Patient follows examiner's finger as they move it slowly in all directions
    • Patient should look up, down, left or right, as well as to eccentric positions (off-center)
  • Nystagmus should be present in all cases of acute vestibular system whether of peripheral or central cause
  • Findings suggestive of peripheral Vertigo
    • Horizontal Nystagmus suggests a peripheral cause (although it does not exclude a central cause)
  • Findings suggestive of central Vertigo (e.g. posterior CVA)
    • Vertical Nystagmus
    • Torsional Nystagmus
    • Nystagmus that changes direction
      • Rightward Nystagmus with rightward gaze
      • Leftward Nystagmus with leftward gaze
• Skew test
  • Perform as with Alternate Eye Cover Test (also used to evaluate for horizontal strabismus in children)
  • Alternately cover one eye and then the other
  • Observe for quick vertical gaze corrections (abnormal)
    • Uncovered eye shifts to center from its abnormal, vertically displaced position
  • Abnormal skew test with quick vertical gaze corrections suggests a central cause (e.g. brainstem CVA)
  • Examiner may also see a head tilt at rest that often accompanies skew deviation

• peripheral vertigo is suggested by:
  • an abnormal (positive) head impulse test
  • unidirectional, horizontal nystagmus
  • absent skew deviation
• central vertigo and thus possible posterior circulation stroke is suggested by:
  • a normal (negative) head impulse test
  • rotatory or vertical nystagmus, or direction-changing horizontal nystagmus
  • presence of skew deviation
• a positive HINTS exam
  • this occurs if at least ONE of the three sections suggest a central cause
  • said to be 100% sensitive and 96% specific for posterior circulation stroke ¹⁾

Head Impulse Test

Direction Changing Nystagmus

Abnormal Test of Skew